GENETIC AND CYTOLOGICAL ANALYSES OF 3 LETHAL OVULE MUTANTS IN SOYBEAN(GLYCINE-MAX - LEGUMINOSAE)

Soybean partially sterile mutants 2, 3, and 4 (PS-2, PS-3, and PS-4), recovered from a gene-tagging experiment, were studied to clarify thei r inheritance, linkage, allelism, and reproductive biology. The PS-2, PS-3, and PS-4 mutants were maintained as heterozygotes and upon self- pollination segregated 1 fertile : 1 partially-sterile. For inheritanc e and linkage tests, all three PS mutants were crossed to flower color mutant Harosoy-w4 and to chlorophyll-deficient (CD) mutants CD-1 and CD-5, also recovered from the tagging study. For allelism tests, recip rocal crosses were made among the three partially sterile mutants. Lin kage results indicated that the gene for partial sterility in the PS-2 ,PS-3, and PS-4 mutants was not linked either to the w4 locus or to th e genes for chlorophyll deficiency. Studies of pollen development, pol len viability, and pollen-tube germination indicated no difference bet ween normal and partially sterile genotypes. Linkage and allelism test s indicated that the gene in the three partially sterile mutants was n ot transmitted through the female when they were used as a female pare nt. A study of megagametogenesis indicated that the ovules from partia lly sterile plants had normal embryo sac development. Ovule abortion w as due to failure of fertilization.